Long-Term Additive Prognostic Value of Thallium-201 Myocardial Perfusion Imaging Over Clinical and Exercise Stress Test in Low to Intermediate Risk Patients

Abstract

Background —The exercise treadmill test (ETT) and Tl201 single proton emission computed tomography (SPECT) are of short- to medium-term prognostic value in coronary heart disease. We assessed the long-term prognostic value of these tests in a large population of patients with low- to intermediate risk of cardiac events. Methods and Results —One thousand one hundred thirty-seven patients (857 men, age 55±9 years) referred for typical (62.1%) or atypical (22.4%) chest pain, or suspected silent ischemia (15.5%), were followed up for 72±18 months. Overall mortality was higher after strongly positive (ST depression >2 mm, or >1 mm for a workload ≤75 W) (2.36%/y) or nondiagnostic ETT (1.63%/y) than after normal (0.85%/y) or positive ETT (1.37%/y) ( P =0.002), and after abnormal SPECT than after normal SPECT (1.60%/y versus 0.68%/y, P =0.001). The major cardiac event rate (cardiac death or myocardial infarction [MI]) was 0.88%, 1.59%, 2.10%, and 2.13%/y after negative, positive, strongly positive, and nondiagnostic ETT, respectively ( P =0.003), and 0.56%, 1.43%, and 2.05%/y in patients with 0, 1 to 2, and ≥3 abnormal segments on SPECT, respectively ( P <0.002). An abnormal SPECT was predictive of MI ( P <0.001), whereas ETT was not. In multivariate analysis, SPECT was of incremental prognostic value over clinical and ETT data for predicting overall mortality and major cardiac events. Conclusions —The incremental predictive value of SPECT is maintained over 6 years and is particularly relevant after positive, strongly positive, and nondiagnostic ETT.